In LTE release (Release) 8/9/10, a physical downlink control channel (PDCCH) is transmitted on first N (N=1, 2, 3, 4) orthogonal frequency division multiplexing (OFDM) symbols of each subframe, and is multiplexed with a physical downlink shared channel (PDSCH) in time-division multiplexing (TDM) mode, and its demodulation pilot is a downlink common pilot, namely, a cell-specific reference signal (CRS). To ensure transmission reliability, a space frequency block code (SFBC) transmission mode or a combination of an SFBC transmission mode and a frequency switched transmit diversity (FSTD) transmission mode is used.
As a heterogeneous network is deployed on a large scale, in LTE release 11, the PDCCH faces great challenges in aspects of capacity, coverage, and interference coordination, and therefore an enhanced PDCCH (E-PDCCH) is put forward. The E-PDCCH is located in a PDSCH region, and multiplexed with the PDSCH in frequency division multiplexing (FDM) mode. In addition, multiplexing of an enhanced control channel and a traffic channel in a time-frequency resource block is not supported. The E-PDCCH is demodulated based on a user equipment (UE) specific demodulation reference signal (DMRS). As may be seen above, time-frequency resources occupied by the E-PDCCH are different from those occupied by the PDCCH in the prior art, and a PDCCH transmission mode cannot be directly used to transmit the E-PDCCH. Therefore, an E-PDCCH transmission problem needs to be resolved.